Battle of Bailen

The Battle of Bailen was fought from 16 to 19 July 1808 during the Peninsular War. In a catastrophic defeat for France, General Pierre Dupont's II Corps was surrounded by Francisco Javier Castanos' larger Spanish army and was forced to surrender, leading to Emperor Napoleon I ordering a general retreat to the Ebro; the great victory at Bailen allowed for the Spanish rebels to recapture much of southern Spain from the French occupiers, but it also led to Napoleon himself intervening later that year and undoing much of Spain's early victories.

Background
French troops managed to take over Spain and Portugal with relative ease in 1808, but rebellions broke out against their occupation almost immediately, leading to the Peninsular War. As Napoleon's French forces besieged Zaragoza, General Pierre Dupont was dispatched to assert French control over the south of Spain. The freshly-minted general and his 13,000-strong II Corps, consisting mostly of experienced Swiss troops or raw recruits, seized Cordoba on 7 June 1808, but the countryside behind Dupont's army rose in rebellion. Guerrilla bands attacked French messengers and supply convoys, threatening to cut off Dupont's army. Dupont was forced to withdraw past the Guadalquivir River, where he was reinforced by two divisions sent from Madrid. At the same time, Spanish regulars and rebels began to rally to Francisco Javier Castanos' 30,000-strong Spanish army. Dupont moved his army to Andujar to prevent Castanos from crossing the Guadalquivir, leaving smaller units to guard the crossing at Mengibar and the city of Bailen.

Battle
On 16 July, Castanos divided his army in two, with the smaller force attacking Dupont's main force at Andujar and the main force under Theodor von Reding attacking Dupont's left flank, commanded by General Louis Liger-Belair. Von Reding's troops outnumbered Liger-Belair's troops three-to-one, and, while Liger-Belair sent messengers to the unit in Bailen under Jacques-Nicolas Gobert to ask for help, the united French forces were driven back from Mengibar, allowing the Spaniards to cross the river. The French troops withdrew from Bailen and then to Guarroman, where they sought to keep the Sierra Morena mountain passes secure. Dupont sent Dominique Vedel with a French unit to assist his left flank on 17 July, and Vedel decided to use the main road to Bailen. However, upon reaching the town, he received a false message that the Spanish were already at La Carolina, forcing him to retreat; however, his messengers were caught before they could reach Dupont, leaving the outnumbered French force divided into halfs. By the night of 18 July, the Spanish had taken Bailen, and Dupont force-marched his troops south from the mountain passes to meet the Spanish. Von Reding and his force awaited him at Bailen, so Dupont ordered a charge, believing that Vedel would assist him once he heard the first gunshots. The French assaults were repelled seven times, while a few thousand of Dupont's Swiss troops defected to Von Reding, their compatriot in Spanish service. Castanos' reinforcements surrounded Dupont and forced him to surrender, and, when Vedel's troops arrived from the north shortly after destroying a few Spanish units, Dupont had Vedel surrender as well.